5-methoxyindoleacetic acid(5-MIAA) is formed through oxidative deamination. It is identified in the urine, and the concentration is determined to be 1.3 micro g/mL using gas chromatography-mass spectrometry.(PMID: 12908946 ). There is increase in urinary 5-MIAA-excretion was shown in patients with cancer of the stomach, rectum and lung. (PMID: 2446428 ).

This compound belongs to the class of organic compounds known as indole-3-acetic acid derivatives. These are compounds containing an acetic acid (or a derivative) linked to the C3 carbon atom of an indole.